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Do late 70's and 80's era coils require ballast resistor?

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Rembrant

Do late 70's and 80's era coils require ballast resistor?

Gents,

I'm just sorting out my new Painless wiring kits and ignition parts trying to figure out what the layout will be, and the Painless Duraspark wiring harness came with a ballast resistor.

https://www.painlessperformance.com/wc/30812

The instructions just say to read the fine print on the coil to see if it requires an external ballast resistor or not. Problem is, the coil I bought doesn't have much fine print, and certainly nothing referencing a ballast resistor.

https://www.rockauto.com/en/moreinfo.php?pk=6280596&cc=1121443&pt=7060&jsn=8046

It's a Spectra Premium C610, that supposedly replaces the OEM Ford part numbers below.

D5AZ12029A, F5028005Z (or, at least the first part number is a Ford number...)

I thought that by late 70's or early 80's that external ballast resistors were no longer required?

Can anybody confirm if it would be required or not? I assume no, but want to be sure.

1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995

Gary Lewis

Re: Do late 70's and 80's era coils require ballast resistor?

Administrator

You are right that there is no external ballast resistor for 70's and 80's Fords. That's because it is buried in the wiring harness, as shown below. It is the 1.1 ohm resistor shown just below the ignition switch.

So since you won't have that you need an external ballast resistor.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

Rembrant

Re: Do late 70's and 80's era coils require ballast resistor?

Gary Lewis wrote

So since you won't have that you need an external ballast resistor.

Alright then, that settles that tuit de suite! Thanks Gary.

I guess I'll wire in the ballast resistor. I also bought the Painless Wiring 21 circuit full chassis wiring harness kit, so everything will be new.

85lebaront2

Re: Do late 70's and 80's era coils require ballast resistor?

Administrator

If you want it to be less obvious, check out some of the Mustang restoration suppliers. The Mustangs used a resistance wire in the dash harness, but it plugged in at both ends. This was to facilitate a tachometer installation as Fords factory one used the positive side for the signal.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

BigBrother-84

Re: Do late 70's and 80's era coils require ballast resistor?

In reply to this post by Gary Lewis

Gary Lewis wrote

That's because it is buried in the wiring harness, as shown below. It is the 1.1 ohm resistor shown just below the ignition switch.

Thanks Gary.
Interesting, I'll remember that.

Jeff / 1984 F350 Crew Cab 4x4/5.8L w351 4V/ T18/ D50 4.10 front/ 8' bed.
Restored 2019-2022.
Nicknamed «Big Brother 1984», due to its soooo-looong shape & nod to George Orwell's 1984 famous novel.

Gary Lewis

Re: Do late 70's and 80's era coils require ballast resistor?

Administrator

Jeff - That drawing makes it look like the resistance wire is easily seen. But it isn't. Somewhere we have a discussion about it and, IIRC, a picture of where it is. However, I can't find it. But I can tell you that it runs in the harness within the dash and is not easily gotten to.

Gary, AKA "Gary fellow": Profile

BigBrother-84

Re: Do late 70's and 80's era coils require ballast resistor?

Thanks for the precision!

Jeff / 1984 F350 Crew Cab 4x4/5.8L w351 4V/ T18/ D50 4.10 front/ 8' bed.
Restored 2019-2022.
Nicknamed «Big Brother 1984», due to its soooo-looong shape & nod to George Orwell's 1984 famous novel.

Rembrant

Re: Do late 70's and 80's era coils require ballast resistor?

In reply to this post by Rembrant

Here is how Painless Wiring has it on their diagram. I'm not 100% sure how this is all going to work yet as I have to find a location for everything first. Also not sure what to do about my ignition switch yet. This truck has an ignition switch with a separate button just for the starter. I might just buy a combo switch from a later truck with the key in the dash, like a 70's truck.

Gary Lewis

Re: Do late 70's and 80's era coils require ballast resistor?

Administrator

That wiring should work nicely. But is the push button on the dash for the starter original? If so I think I'd leave it. If not, I'd do as you said and use a later switch with start included.

Gary, AKA "Gary fellow": Profile

Rembrant

Re: Do late 70's and 80's era coils require ballast resistor?

Gary Lewis wrote

That wiring should work nicely. But is the push button on the dash for the starter original? If so I think I'd leave it. If not, I'd do as you said and use a later switch with start included.

Hey Gary,

Yes the push button start is original. The ignition switch is really just a power switch. I was thinking of converting it to a later style dash ignition switch, like from a first gen Bronco or a pickup mainly for simplicity, but since I have modified the original steering column, I no longer have a horn, so I was thinking of converting the starter push button to a horn button.

We'll see. I'll see how it all looks when I start chopping the original wiring away...

Gary Lewis

Re: Do late 70's and 80's era coils require ballast resistor?

Administrator

Yes, that would work nicely. The original start push button would probably look "factory" but would serve well for the horn.

Gary, AKA "Gary fellow": Profile

ArdWrknTrk

Re: Do late 70's and 80's era coils require ballast resistor?

Administrator

This post was updated on .

In reply to this post by Gary Lewis

I'm pretty sure it was our British member Matt mentioning that he found the wiring hot up inside the dash. ("Dash on fire" or something like that)
IIRC I suggested an IR thermometer or a FLIR camera to narrow down the problem.

The thick pink wire was located up by the A pillar.

Edit: here it is. https://forum.garysgaragemahal.com/Pre-Emptive-FIRE-tp58908.html

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: Do late 70's and 80's era coils require ballast resistor?

Administrator

Good job, Jim! Yes, I thought it was Matt, but even then I couldn't find it. Well done!

Gary, AKA "Gary fellow": Profile